1. Field of the Invention
The invention pertains to sash balances, more particularly to a sash balance that is attached to a sash and contains a block and tackle and spring in a housing that moves with the sash as the housing moves along a window frame track and locks in the track when the sash is tilted out of the track.
2. Description of the Prior Art
Various brake shoe designs that attach to a sash by a pivot on the sash and include an element connected to the pivot that locks against a window frame track when the pivot is turned by the sash rotating out of the window frame, are hung from lifting devices that are mounted on the window frame above the shoe.
Damani, U.S. Pat. No. 6,467,128 describes a block and tackle in which the sash pivots on a bearing that is at the end of the cord that extends out of the bottom of the balance assembly housing.
In Prosser, U.S. Pat. No. 4,190,930 the sash rests on a sloping surfaced shoe that is at the end of the cord that extends out of the bottom of the balance assembly housing, or on a sloping boss that extends laterally from the bottom of the housing.
Wood, U.S. Pat. No. 4,068,406 describes a block and tackle in which the sash pivots on a brake shoe that hangs from the end of the cord that extends out of the bottom of the balance assembly housing.